Many automatic transmissions have fluid-operated clutches which have the inner surface thereof slidingly sealed by a lip type seal. The lip seal is installed in a groove formed in a shaft member and the piston is installed over the seal. During installation, it has been found that under certain circumstances, the lip seal will tend to roll and therefore be ineffective as a sealing member in the transmission.
Generally, this error is discovered during testing of the transmission and/or clutch pistons prior to removal from the plant installation into an automobile. However, under some instances, the lip seal is partially rolled and the leakage is slow, such that the error is not found until after the vehicle has been in operation for a while.